1. Field of the Invention
The present invention relates to a cooling system and a cooling method.
2. Description of the Related Art
Recently, with the improvement in the information processing technology and the development of the Internet environment, required amounts of information processing have been increasing, and the business of the data processing center for massive processing of various types of information has been in the spotlight. For example, in the sever room in the data processing center, a great number of electronic devices are arranged in a centralized manner, and are continuously operating day and night.
By the way, the rack mounted system is currently the mainstream of the system for placing electronic devices in the sever room. In the rack mounted system, electronic devices are classified on the basis of their functions, housed in chassis or racks on a function-by-function basis, and stacked in racks or cabinets. On the floor of the sever room, a number of racks or cabinets in which electronic devices are mounted as above are disposed.
Incidentally, when electronic devices are placed in a high-temperature environment, the possibility of occurrence of a trouble such as a system stop increases. Therefore, it is necessary to suppress the environmental temperature below a predetermined value. However, since the processing capacities of the electronic devices have been rapidly improving, the amounts of heat emitted from the electronic devices keep on increasing.
Actually, the air-conditioning power needed for cooling the sever room is greatly increasing, and reduction of the air-conditioning power is urgently necessary from the viewpoint of conservation of global environment as well as the viewpoint of cost reduction in business management.
For example, Japanese Patent Laid-open No. 2006-507676 (which is hereinafter referred to as Patent Literature 1) discloses a cooling system in which a rear cover, a front cover, and a cooling-air subframe are arranged around an electronic device. In addition, Patent Literature 1 discloses that a fan and a heat exchanger are arranged in the cooling-air subframe, and cooling air is caused to flow in a closed loop through the electronic device.
Japanese Patent Laid-open No. 2004-232927 (which is hereinafter referred to as Patent Literature 2) discloses that an electronic device is cooled by absorbing heat with an evaporator which is mounted inside a rack provided for housing the electronic device, and heat is discharged rearward or upward from a water-cooled condenser, which is mounted on the back side of the rack provided for housing the electronic device.
Japanese Patent Laid-open No. 2007-127315 (which is hereinafter referred to as Patent Literature 3) discloses a cooling system which performs cooling by causing natural circulation of a refrigerant between a water-cooled condenser and a heat exchanger for cooling, and using the latent heat of evaporation of the refrigerant which flows through the heat exchanger for cooling.
According to the techniques disclosed in Patent Literatures 1 and 2, although the cooling can be assisted by arranging a cooling system around the electronic device, the cooling system consumes air-conditioning power. Therefore, there is room for improvement in the above techniques from the viewpoint of energy saving.
In addition, according to the technique disclosed in Patent Literature 3, although the refrigerant is naturally circulated, only the low-temperature liquid from an ice storage can supply cold to the refrigerant gas flowing through the water-cooled condenser. Therefore, there is room for improvement in energy saving performance.